Life science and analytical instrumentation are designed to determine the identity and structure of inorganic and organic liquids and gases, and then detect, separate and analyze their individual compounds.

These processes require the application of heat to the sample. Very specialized heating elements are normally required to achieve the temperatures (300 deg. C to 500 deg. C) to achieve breakdown of the samples into base components. Since sample sizes are normally very small, the heating elements must also be small, react quickly, and be easy to control.

PID control stands for proportional, integral and derivative and is a very common control mode used in process control and manufacturing. PID is used in process loops such as pressure control, temperature control, flow and level control. It is also used in robotics, as shown here.

A better description, from Wikipedia, is the continuous calculation from "an error value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error over time by adjustment of a control variable, such as the position of a control valve, a damper, or the power supplied to a heating element, to a new value determined by a weighted sum".

The video below provides a detailed explanation into how PID control works.

Pressure/Vacuum Relief Valves are protection devices typically mounted on a nozzle opening on the top of a fixed roof atmospheric storage tank. Their primary purpose is to protect a tank against rupture or implosion by allowing the tank to breathe, or vent, when pressure changes in the tank due to normal operations.

Pilot Operated Relief Valves serve the same primary purpose as pressure/vacuum relief valves, but with better performance characteristics than weight or spring loaded valves. Lower leakage and better flow performance make a pilot operated valve the solution when the focus is product conservation, expanded tank working band, and reduced fugitive emissions. A pilot operated relief valve provides the maximum available leakage control technology as specified in the Clean Air Act of 1990.

Deflagration Flame Arresters are fire safety devices used to protect stored or process media from deflagrations. A deflagration flame arrester can be used on the top of a tank or as an in-line safety device where combustible gases are transported through low pressure pipe lines.

Detonation Flame Arresters provide flame protection in cases where the ignition source pipe lengths are greater than what can be protected with a deflagration arrester.

Blanket Gas Regulators can provide both pressure and fire protection for storage tanks by supplying a blanketing gas which maintains a constant positive pressure in the vapor space of a storage tank. In addition to preventing outside air and moisture from entering the storage vessel, a blanket gas regulator reduces the evaporation of the stored product to a negligible amount, resulting in product conservation and greatly reduced emissions.

Tuesday, December 29, 2015

Society has benefited tremendously from the development and utilization of mechanical devices which are implanted inside the body and are used to replace bones and joints, increase blood flow, and even measure blood chemistry. To further enhance the performance of these devices, the application of thin films to the external surfaces is an ongoing research and development interest at many companies.
Engineers have a choice of a variety of technologies to apply these liquid coatings to these often complex surfaces ranging from vacuum technology to direct liquid application. The decision on what technology to use is a function of the liquid precursor used, the mechanism of coating formation and the geometry of the object to be coated. A critical quality and process control criterion is the consistency of the coating on the surface. Fluid delivery technology can play an important part in maintaining coating consistency. Pumps and liquid flow controllers are technologies being used today. For vapor coating processes, liquid vaporization technology is a critical link in the fluid delivery system. New flow and vaporization technology is available that can be applied to fluid delivery to improve the application of medical device coatings.

Why Coating

The human body has defense mechanisms that normally treat foreign objects as a threat. This is great when the foreign body is a bacteria or a virus, but in relation to medical devices, this response can affect their performance. Certain metals and plastics have surface properties that make them somewhat compatible in the body. In many applications, these materials don’t have the proper physical properties to make them useful for a specific function. Other materials might be better from a mechanical standpoint, but are more irritating to the body. Coatings are also used to extend the useful life of the device in the body. Here are just some of the uses of medical coatings.

To reduce friction of the medical device in the body to improve the placement of the device and also minimize irritation and inflammation

To reduce the formation of scar tissue surrounding implanted devices

To encourage the growth of tissues to help the healing process

To reduce the chance of infection related to the implanted device

To “hide” the device from the body’s self defense mechanism

To measure body chemistry in real time

The coatings applied to the surface can be as simple as a thin metal coating or as complex as polymer coating interlaced with precise pores that time-release drugs.

Coating Challenges and Solutions

Applying a coating to a device that is placed in the body is a very critical process. The potential detrimental affects of the coating must be thoroughly investigated prior to official approval for market introduction. Here are some of the many challenges facing an engineer when designing techniques for coating medical device structures.

The reliable identification of low combustion oxygen in a fired heater or boiler has always been critical to the effectiveness of the Burner Management System for proper control and safety.

Low emission burners and aggressive firing control points to achieve increased efficiency and emission reductions have driven the industry to tighter control measures. But tighter control measures also hold a greater potential for combustion events. Reducing the risk of a combustion event has become a priority and has led to the implementation of Safety Instrumented Systems (SIS). This additional layer of safety is added to the Basic Process Control System.

The WDG-V has been designed to provide an additional layer of safety with the measurement of excess O2, Combustibles and Methane and by using these measurements to ensure the safe operation of the Burner Management System.

WDG analyzers are based on a zirconium oxide cell that provides a reliable and cost-effective solution for measuring excess oxygen in flue gas as well as CO and methane levels. Information from the Gas Analyzer allows operators to obtain the highest fuel efficiency, while lowering emissions for NOx, CO and CO2. The zirconium oxide cell responds to the difference between the concentration of oxygen in the flue gas versus an air reference. To assure complete combustion, the flue gas should contain several percent oxygen. The optimum excess oxygen concentration is dependent on the fuel type (natural gas, hydrocarbon liquids and coal).

Thursday, December 10, 2015

Intrinsic Safety Barriers are devices that limit power delivered from a safe area into a hazardous area. The possibility of an explosion is prevented, not merely contained (by a housing or a conduit). The total energy is maintained within safe limits, not electrical energy (voltage and current), eliminating an ignition from excessive heat. The use of an intrinsically safe design offer many cost and safety advantages.